Three-dimensional integrated circuits (3DICs) were commonly used, wherein two dies may be stacked, with through-silicon vias (TSVs) formed in one of the dies to connect the other die to a package substrate.
In conventional processes, an interposer wafer is provided first, with TSVs formed in the substrate of the interposer wafer. An interconnect structure is formed on one side of the interposer wafer. Next, a first carrier is mounted onto the interposer wafer. The Substrate is then thinned, until the TSVs are exposed. Solder bumps are then formed on the interposer wafer and electrically coupled to the TSVs.
Next, the first carrier is de-mounted from interposer wafer, and a second carrier is mounted onto interposer wafer. The first and the second carriers are mounted on opposite sides of the interposer wafer. Dies are then bonded onto interposer wafer, and the second carrier is de-mounted. In this process, two carriers are needed, which require two mounting steps and two de-mounting steps. The manufacturing cost is thus high.